Journal of Parasitic Diseases: June 2006, Vol. 30, No. 1, 94–97Short communicationJ P DField evaluation of a rapid immunochromatographictest kit <strong>for</strong> the diagnosis of Plasmodium falciparum andnon-falciparum malaria parasites from Sonitpurdistrict, AssamC. Rajendran and S. N. DubeBiotechnology Division, Defence Research Laboratory, Tezpur.ABSTRACT. <strong>The</strong> sensitivity and specificity of ICT Parascreen test kit device (rapid test <strong>for</strong>malaria pan/Pf) was compared with conventional microscopic method as the gold standard. A totalof 126 patients were tested with ICT and microscopic blood-smear examination. Sixty one(48.41%) patients were found to be positive <strong>for</strong> malaria infection in microscopic examination. Withthe ICT kit, the sensitivities and specificities <strong>for</strong> Plasmodium falciparum and non-falciparum (P.vivax) parasites were 96.30 and 88.88%, and 98.48 and 98.48 %, respectively. <strong>The</strong> ICT kit gave alittle lower sensitivity as compared to microscopic examination.Keywords: HRP II, ICT Parascreen test kit, malaria, pLDHGlobally, malaria still remains a major parasitic microscopic method (WHO, 1996). <strong>The</strong> ICT is a RDTdisease with high morbidity and mortality. In the <strong>for</strong> P. falciparum specific HRP II antigen (Parra et al.,Northeast region of India, the endemicity of malaria 1991) and a pan malaria antigen (Garcia et al., 1996).infection and the predominance of Plasmodium RDT is very much useful where microscopy is lackingfalciparum over P. vivax is now well documented (Dev and where the malaria is severe (WHO, 2000b). <strong>The</strong>and Phookan, 1996; Kamal and Das, 2001). Accurate conventional microscopy is the gold standard test todiagnosis and proper treatment, which are important diagnose malaria infections worldwide. Even thoughto the control of malaria, are the main aims of the it is sensitive and economical, several disadvantagesglobal malaria control strategy (WHO, 2000a). Based make it inconvenient <strong>for</strong> use in the field viz.,on clinical symptoms alone, malaria and non-malaria requirement of electricity, trained microscopyfebrile cases and the species of Plasmodium can not be personals and difficulties in accurate speciesdistinguished (Chandramohan et al., 2001). Further, identification as evidenced by sensitive molecularaccurate diagnosis of malaria is essential to make a methods. Currently, rapid ICT cards are available torational choice of drug <strong>for</strong> the treatment. <strong>The</strong> detect malaria infection upto species leveldevelopment of Rapid Diagnostic Tests (RDT) <strong>for</strong> (Wangsrichanalai, 2001). <strong>The</strong> first generation ofmalaria based on immunochromatographic test (ICT) detection kits was designed to diagnose only P.strips provides a valid alternative to conventional falciparum, but now the newer devices have beendesigned to diagnose both P. falciparum specificCorresponding author: Dr. Rajendran, Biotechnology Division, antigens as well as Plasmodium genus specificDefence Research Laboratory, Post Bag No. 2, Tezpur-784 001, antigens. Early detection and differentiation ofAssam, India. E-mail: chellairajendran@rediffmail.com malaria is of paramount importance due to the
Immunochromatographic test kit evaluation <strong>for</strong> malaria diagnosis95incidences of cerebral malaria and drug resistance smear examination. Out of these 61 positive samples,associated with falciparum malaria, and due to the 52 were found positive <strong>for</strong> P. falciparum (85.24 %) andmorbidity associated with the other malaria <strong>for</strong>ms. So, 9 were positive <strong>for</strong> non-falciparum parasite (P. vivax;ICT kits are considered <strong>for</strong> malaria diagnosis as 14.75 %), whereas the Parascreen ICT kit showed 54microscopic method has limitations. So far, field samples positive <strong>for</strong> P. falciparum and eight <strong>for</strong> P.evaluation of ICT kits has not been done <strong>for</strong> its use in vivax. A summary of the findings by these two tests hasimmediate clinical management of malaria in Sonitpur been given in Table I. <strong>The</strong> sensitivity and specificitydistrict, Assam. <strong>The</strong>re<strong>for</strong>e, the present study was values of the ICT were calculated using the results ofundertaken to study the per<strong>for</strong>mance of the ICT kit in microscopic examination as the gold standard. As perthe field by comparing it with the gold standard the Parascreen ICT kit, the sensitivity and specificitymicroscopy method.<strong>for</strong> P. falciparum and non-falciparum (P. vivax)parasites were 96.30 and 88.88 %, and 98.48 and 98.48<strong>The</strong> study was conducted at seven different places of%, respectively.Sonitpur district, Assam, between August 2004 andMay 2005. Each patient, who was suffering from <strong>The</strong> present field study revealed that the ICT kit couldfever, was finger pricked by using a sterile lancet. detect P. falciparum from 54 cases, whereas lightThick and thin blood-smears were prepared and microscopy showed 52 positive cases. Among the 54stained with Giemsa according to standard cases, two blood-smears were found negative <strong>for</strong> P.procedures. <strong>The</strong> thick smear was used to detect the falciparum but the ICT was positive <strong>for</strong> them. <strong>The</strong>infection, whereas the thin smear was used <strong>for</strong> species possible reason could be due to the persistence ofidentification. A blood sample was considered PfHRP II following the clearance of P. falciparumnegative, when no parasite could be detected in 100 (Wongsrichanalai et al., 1999). But <strong>for</strong> the case of nonfieldsof an oil immersion (x1000 magnification) falciparum (P. vivax) parasite, the ICT kit could detectobjective lens of a microscope (Fernando et al., 2004). only eight cases out of nine found by microscopicalAt the same time, approximately 5 µl of whole blood method. Generally, irrespective of the manufacturers,from finger prick of the patient was transferred the sensitivity and specificity <strong>for</strong> non-falciparum,directly to a sample pad. For testing the sample, ICT with the available ICT kit, is varying from 50-70% andParascreen test kit (Zephyr Biomedicals, India) was 37.580%, respectively, as compared to microscopy.used as rapid diagnostic device (Lot No: 101003, Mfg But the present study revealed 88.88% sensitivity andDt: 08-2004 and Exp. Dt: 07-2006). Parascreen 98.48% specificity. This study was conducted basedutilizes the detection of P. falciparum specific on qualitative assessment but not quantitative one ashistidine rich protein II, which is water soluble protein the accurate counting of parasites was not carried outthat is released from parasitized-erythrocytes of to assess the correlation of the sensitivity. Butinfected individuals, whereas <strong>for</strong> the detection of pan increasing sensitivity of the test with increasingmalaria, Parascreen detects the presence of pan parasite densities is one of the main factors inmalaria specific pLDH released from the parasitised detecting parasites (Mason et al., 2002). Variouserythrocytes. <strong>The</strong>n, a drop of buffer was added and authors have reported different degrees of sensitivityallowed to react <strong>for</strong> 2 min. This buffer was added to and specificity of P.f/P.v test kit manufactured frominduce cell lysis and allow PfHRP II and pan-malarial different countries and from different localities.antigens to bind to colloidal gold-labeled monoclonal Palmer et al. (1998) evaluated OptiMAL test <strong>for</strong> theantibodies. All tests were considered as valid if a diagnosis of P. falciparum and P. vivax malaria, and itcontrol line was observed. <strong>The</strong> sensitivity and uses a monoclonal antibody to the intracellular antigenspecificity was calculated as per the <strong>for</strong>mula given by parasite lactate dehydrogenase (pLDH). ItMason et al. (2002). <strong>The</strong> sensitivity was calculated as differentiates species by the use of a P. falciparumthe number of true positives by the test divided by total specific and a genus specific antibody. It has shown 88positives by Giemsa [TP/(TP+FN)], and the and 94% sensitivities on symptomatic Honduranspecificity was determined as true negatives divided patients and specificities of 100 and 99% <strong>for</strong> theby the false positives (TN/TN+FP).diagnosis of falciparum and vivax malarias. Beatriz Eferro et al. (2002) evaluated OptiMAL and gave aA total of 126 blood samples were collected. Amonghigher efficiency of 98.1% <strong>for</strong> P. vivax than 94.9% <strong>for</strong>these, 61 (48.41 %) samples were found positive <strong>for</strong>P. falciparum, in a malaria referral center in Colombia.malaria infection by standard microscopical blood-But Mason et al. (2002) evaluated two test kits viz,
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